1. Field of Invention
The present invention relates to a power converter, and more particularly, the present invention relates to a control circuit having a multi-function terminal of power converter.
2. Description of Related Art
FIG. 1 shows prior art of a power converter. The power converter comprises a boost converter 30, a controller (CNTR) 50, a thermal device 40 and a voltage divider developed by resistors 41 and 42. The boost converter 30 includes an inductor 10, a transistor 15, a rectifier 20 and a capacitor 25. One terminal of the inductor 10 receives an input voltage VIN. The other terminal of the inductor 10 is connected to an anode of the rectifier 20 and a drain of the transistor 15. A source of the transistor 15 is connected to a ground. A gate of transistor 15 is coupled to a switching terminal SW (not shown) of the controller 50 and controlled by a switching signal SW. A cathode of the rectifier 20 is connected to one terminal of the capacitor 25. The other terminal of the capacitor 25 is connected to the ground. An output voltage VO is generated across the capacitor 25 and is the same as an output of the boost converter 30. The output of the boost converter 30 is also an output of the power converter.
The controller 50 generates the switching signal SW to switch the transistor 15 for producing the output voltage VO of the power converter. A feedback signal VFB is generated at a joint of the resistors 41 and 42 of the voltage divider in response to the output voltage VO. The feedback signal VFB is applied to a feedback terminal FB (not shown) of the controller 50 for generating the switching signal SW and regulating the output voltage VO. An over-temperature signal SOT is generated from the thermal device 40 coupled to the controller 50 for over-temperature protection. That is to say, the controller 50 performs over-temperature protection in accordance with the over-temperature signal SOT generated by the thermal device 40.